Pump



' July 29 1924. 1,503,458

K. L. CURTIS I PUMP Original Filed Feb. 28, 1922 3 Sheets-Sheet 1 INVENTOR BY m [/Vdm/ 3002 GD ATTORNEYS July 29, 1924. 1,503,458

r K. L. CURTIS PUMP inal Filed Feb. 28, L922 3 Sheets-Sheet 5 1N VENTOR TTOR NE 3 5 wan W (jar/M 40 ing to 2-12 July 29, I924,

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KENNETH L. CURTIS, OE YORK, N. Y;

Original application filed February as,

To all whomfit may concern:

Be it known that I, KENNETH L. Cun'rrs, a citizen of the United States, and resident of the city of New York, borough of Manhat- 5 tan, county and State of New York, have invented certain new and useful Improvements in Pumps, of which the followmg 1s a s ecification.

-y invention relates to pumps and the invention is especially adapted to vacuum pumps for creating and sustaining a relatively high vacuum.

The invention was developed in connect on with refrigerating apparatus for maintaining a vacuum over a body of water used as a refrigerant in a closed chamber, and in order to more readily understand the operation and advantages of the invention it will be described in connection with said rel frigerating apparatus;

. This application is a div1s1on of my co-. ending application, Serial No. 539,881,'filed ebruary 28, 1922, for process and apparatus for refrigeration, and the claims of this application are directed to the pumping apparatus as such.

One of theobjects of the invention is to produce an eficient vacuum or suction pump apparatus. In the preferred emso bodiment of the invention shown and described, the vacuum pump is provlded with a zero-clearance outlet valve and a mechanically operated inlet valve, a combination which provides a very efiiclent and durable ae. pumping apparatus for the Purpose intended.

The invention consists in novel features, arrangements, constructions and combinations of arts hereinafter described accordthe present preferred embodiment thereof and the invention will be more particularly pointed out in the appended claims.

Further objects and advantages of the in.-

' vention will more fully appear from the following description taken in connection with the accompanyin drawings, illustrating by way of examp e the preferred embodiment of the invention and in which Fig. 1 represents a somewhat diagrammatic view, partly in side elevation and. partly in section, of the entire apparatus;

Fig. 2 is an enlarged section takenon lines '22 of Fig. 1 illustrating-the vacuum 1922, Serial No. 5%,881. Divided and this application filed August 16, 1922. serial No. 582,128.

pumping apparatus atone point in its opf In accordance with the invention a liquid refipigerating medium, preferably water,

into a chamber which is located in a space to be cooled. I have illustrated a closed chamber, or container, 1, located within a refrigerator 2 adapted for. containing food etc., as in the usual domestic ice box,

or refrigerator. The container 1 is preferably located within the refrigerator near theupper portion of the interior thereof,

and may be supported b suitable supports 3, 3, which are preferab y spaced inwardly somewhat from the .outer walls of the refrigerator. The liquid refrigeratin medium,.preferably water, as stated. is ed into the chamber 1 by a pipe 4. Means must be provided for maintaining the supply of liquid to chamber 1 to compensate for vapors which are withdrawn therefrom during the refrigerating process. Preferably the water or liquid level is maintainedat a constant desired level, as illustrated for exam le at 5, by means of a float valve, the V vs- 6 being illustrated as pivoted to the wall of container 1 and having an arm.7 carrying afloat 8 secured thereto, the valve 6 closing when the liquid reaches the desired level an opening when. the level falls, in the well lmown manner.

. A suction pump is connected by pipe 9 to the interior of container 1;. A partial vacuum is formed in chamber 1'by the 0 eratlon of this pump which causes the re igeratmg medium to evaporate and thus to give up heat, the amount of heat removed being practically proportional to the amount of vapor remove from chamber .1. When water is used as the refrigeratin medium,

as is preferred, no provislon nee 'be made for condensing and using the same again.

It also may be noted thatthe thermostat and pressure control devices which are essential to the successful operation of various automatic refrigerating apparatus now in use, are not needed.

The chamber 1 is preferably provided with a plurality of pipes 10 extending there through and opening at both ends into the space to be refrigerated. The members 3 which serve as supports for chamber 1 also preferably serve as partitions extending from sideto side of the refrigerator with openings at the bottom thereof, so that when the device is in operation the warmer air will pass upwardly, through the space between partitions 3 and the outer walls, pass downwardly through the pipes or passages 10 where the heat is abstracted, and through the'holes in shelves 12 and openings 11, the air then again passing up along the outside passages. The refrigerator may be provided with perforated shelves 12 in the usual manner.

The vacuum pumping apparatus is shown as contained within thecylinder' 13 and the crank case 14. The vacuum producing 'or suction apparatus is particularly well adapt ed to produce an exceedingly low vacuum in chamber 1, which is necessary for or highly desirable inthe operation of the system.

The vacuum pump which is preferably used combines a zero-clearance outlet valve and a mechanically operated inlet valve. The zero-clearance is obtained by making the outlet valve extend over the full diameter of the cylinder so that the piston may move to ,the extreme end of the cylinder or even overtravel without doing any damage. The inlet valve preferably takes the form of a sleeve which seals the inlet opening by seatin at its end in the manner of a poppet va ve and not by sliding over a port to entirely cover or uncover the same, as is one tomary with sleeve valves. By the use of a mechanically operated inlet valve and an outlet valve of the character referred to I am able to obtain great efiiciency and may produce an exceedingly low vacuum. By a mechanically operated inlet valve I mean one which operates by mechanical means, independently of any difference of pressure on the opposite sides of the same, so that operation of the same will be certain even when operating under conditions of such extreme vacuum, that there would not be enough pressure on either side of a valve to open the same at anytime.

In the preferred form of the apparatus, as'illustrated, the vacuum 'pump apparatus comprises a pair of cylinders 13' and 15 which are secured to an air tight crank case 14, the. cylinder 13 being shown as mounted on the upper end of the crank case, with-its lower end opening into the same, while the cylinder 15 is mounted within the lower portion of the crank case. The pistons of the two cylinders are connected to operate in unison, the piston 16 of the upper cylinder serving to draw water vapor, or generally of the upper cylin er and 23 in the case of the lower cylinder, and are opened at the end of each outward piston stroke, by the pressure of the exhaust gases or vapor, or condensed liquid in the case of the lower cylinder, during the regular operation of the chamber.

The inlet valves both preferably take the form of sleeves as shown, the sleeve valve of the upper cylinder 13 being indicated. at 24 and the sleeve valve of the lower cylinder being shown at 25. These sleeves surround the pistons and form in effect the cylinder walls. The upper sleeve 24 is preferably provided with an inclined surface 26 at its upper end which is adapted to seat against a correspondingly shaped surface 27 on the valve seat 28, while the lower sleeve 25 is providedwith a-similarly shaped lower end surface 29 which seats against a similar seating surfaceon the seat 30. The sleeves are preferably moved in one direction by a cam or similar mechanical device and in the other direction by springaction.

The cylinder 13 is provided with a valve chamber casing 13 and between the cylinder and this casing there is interposed (see Figs. 46) member 28' the inner portion of which preferably serves as the said valve seat 28. The casing is detachably secured to the cylinder 13 in any suitable way, as for example by .the bolts 13". Valve chamber 15' of lower cylinder 15 is likewise detachably secured to said cylinder by bolts not shown, and the valve seat member of this cylinder is also arranged between the cylinder and valve chamber as above described in connection withthe main cylinder 13.

In the preferred form of the device, as illustrated, the two cylinders 13 and 15 are diametrically opposed to each other and the two pistons are operated in unison from the same wrist pin. As illustrated the two pistons may be connected together by a rod 31 in axial alignment with both of the same, a connecting rod 32 being pivotally connected at its upper end to a pin 33 on piston rod 31 while the lower end of the connecting rod 1s pivotally connected to the pin 34 on a disc'35 secured to the shaft 36 which is con stantly rotated from a suitable motor or powerdevice.

The two sleeves 24 and 25 are connected same, (see Fig. 4). Disc is'preferably v springs being indicated at 43 secured at their formed asa cam or eccentric, a roller 40. resting against the outer surface thereof. Preferably roller 40 is carried by an arm 41 havingdownwardly extehding portion 44 above the cam,disc..35, arm 41 being pivotally secured at its outer end, at 42 to the crank case. The cam disc and roller 40 are utilized for moving the sleeve valves in one direction, while sprin s are used for moving the sleeves in the ot er direction, suitable opposite ends to the clamping member 38 and the cylinder 15.

A push rod 45 for actuating thesleeve valves'rests on or is secured to the upper portion of arm 41. Preferably push rod 45 is formed as a tube, for a purpose to be explained hereafter, this tube extending through a suitable-opening in the clamping member 37, through an aligned opening in the top member 46 of the crank case and into an aligned bore or passage 47 formed in cylinder 13, in which it is guided.

Preferably push rod 45 operates the sleeve valves through a spring 48 (see Figs. 2 and 3), which must be sufficiently stitl to move the sleeves against the pull of springs 43 and yet be capable of being compressed by a slight overtravel of ush rod 45 itself, so as to prevent possible damage of the parts in case the push rod tends to overtravel slightly for any reason; Spring 48 may surround the rod or tubular member 45 betweena cup or abutment 49 secured to the rod, at one end, and a cup 50 at'the other end which bears against the clamping member 37. Ac-

cordingly both sleeves Wlll be moved upwardly by cam 35 and will be moved downwardly by springs 43 as soon as such movement is permitted by cam 35 during each operation of the pistons.

In the operation of the device as so far described, the pipe connection 9 which leads to the evaporating chamber 1 in the refrigerator, is connected through the opening 51 in the upper head of cylinder 13 with a passage 52 which leads into the interior of cylinder -13,'above.piston 16, when sleeve 24 is away from itsseat 27, as shown in Fig. 6.

In the regular operation of the system, air and water vapor, or other gases, will. be sucked into the space above piston 16 onthe descending stroke'of the latter, as shown in Figs. 3 and 6, inlet valve 24 .then being opened and outlet valve 20 closed. Valve 24 will be moved upwardly against its seat about the time that piston 16 starts on its return or upward movemen't so that outlet valve 20 will be moved from its seat against the pressure of. springs 22 and the, contents of the cylinder above the piston will be forced into passage 47 previously referred to. The gases pass from passage 47 into the tubular member 45 which extends into the lower end of the same and pass out through an opening 53 in member 45 into the interior of the air tight crank case.

Piston 17 of the lower cylinder will be rising on its intake stroke as the upper piston is moving upwardly on its expelling stroke. Condensed water, or air and gases in the crankcase, and surplus oil will pass through an opening 54 which extends through cyli nder 15 of the lower pump member mto an annular space 55 formed in the cylinder 15 surrounding sleeve 25. The

sleeve being raised from. its seat, as shown in Fig. 2, this material will be drawn into the interior of the cylinder, and when sleeve valve 25 closes and piston 17 descends, the .putlet valve 21 will open and this material will be forced out through pipe 18 into the container 19 shown in Fig. 1.

It will be noted that the outlet valves 20 and 21 of the two cylinders extend across the entire diameter of the cylinders and constitute what may be termed zero-clearance outlet valves, since the pistons may travel on their exhaust strokes to the full end of the cylinders, or may even overtravel. Valves 20 and 21 may be considered as movable cylinder heads.

' The pump pistons are designed to operate at high speed in the system described, and

considerable power would be required if the upper piston had to operate at this speed to withdraw air from chamber 1 at the beginning of the operation, when the entire system is filled with air at atmospheric pressure. I the evaporating chamber 1 by the large. upper cylinder and discharged into the crank case would be more than the smaller lower cylinder could remove in time to prevent the building up of a'high pressure in the crank case, which would further increase the power required. Accordingly in the preferred form of the invention the lower cylinder alone is utilized at the beginning of the operation; the lower cylinder then withdrawing air from the interior of the crank case and through connection 47 and a bypass connection 56 from the container 1. Pum

Also the air thus drawn from cylinder 15 is considerably smaller in d1 &

- pass 56 extends from the inlet opening 51 (Fig. 5) through a valve opening 56 57, into the space 58 at the upper end of the cylinder in which the outlet valve 20 is seated, this space 58 opening into the passage 47 which leads to the crank case. A valve 59 is positioned to seal the opening 56 extend ing from the horizontal portion of by pass 56 into the recess 57, when a suflicient vac uum has been established in the system, so as to shut off the bypass.

This valve 59 rests on a pile of air tight containers 60 which rest on a support 61 which extends across the construction within space 58. Containers 60 are thin hollow members, of what may be termed pill box construction, preferably formed of very thin metal. -They are filled with air at atmos pheric pressure, and will lie flat on each other on support 61 when the pressure surrounding them in space 58 and bypass 56 1s atmospheric, in which case an opening will be provided over and around the containers, as is shown in Fig. 5. When this condition exists the lower pump cylinder will draw directly through passage (17 and bypass 56, from chamber 1, and the upper pump cylinder will be ineii'ective. After the lower pump has operated sufficiently to reduce the pressure in the crank case, containers 60 will expand because of the unbalanced pressure of the air confined inside the same, and valve .59 will be lifted and held against its'seat at the top of space 57, as is shown in F1 6,.

whereby the ypass 56 will be closed an the upper pump cylinder rendered effective.

11 the preferred construction of apparatus the wrist pin 33 (Figs. 2 and 3) 1s preferably; mounted between ball bearing 62 and the crank pin is similarly provided with ball bearings, (not shown). The crank shaft 36 is preferably provided with a step bearing 63 to take the thrust caused by the vacuum in the crank case, the step bearing forming a seal'and preventin air from leaking into the crank case at t is point. Oil may be supplied to the face of the step bearing through pipe 64, the oil bein slowly sucked into the crank case along-t e surface of, the crank shaft 36 and thereby lubricating the crank shaft.

The remaining parts of the pumping apparatus are preferably lubricated by a single oil supply pipe 65, indicated in Figs. 1 and A, which supplies oil to an annular recess 66 located between the upper cylinder sleeve 24.- and the cylinder casing 13. This oil is sucked upwardly into the upper space 58 surrounding sleeve 94 whence it flows over theupper edge of sleeve 24, when open, into the cylinder above the piston. Oil is also sucked down from recess 66 into the crank case, where it is splashed by the crank disc 35 so as to reach every moving part in the crank case.

The receptacle 19 into which the lower cylinder 15 discharges serves as an oil reservoir and also as a separator to recover the surplus oil from the discharge of the pump. The condensed water vapor from the crank case, when water is the refrigerating fluid used, settles to the bottom of vessel 19, as is indicated at 66', the oil rising above the water, as is indicated at 67. The oil is drawn upwardly from this space by pipe 65, previously referred to, and is used over again. The water is forced upwardly in a trap 68, by the weight of the V oil 67 above the same in vessel 19, the water flowin out through a pipe 69 intrap 68.

The re rigerating apparatus described is inherently self regulating, because as the temperature of the water chamber 1 is lowcred, the water vapor withdrawn therefrom through pipe 9 becomes. less dense and as the amount of cooling produced in chamber 1 at a given pumping speed is directly proportional to the amount of vapor removed, it is directly proportional to the density-of the vapor. For example at 40 degrees F. temperature one pound of steam occupies 2438 cubic feet, and at 32 degrees F. it occupies 3294 cubic feet. The removal of one pound of steam will produce practically the same amount of cooling at either temperature.

When a greater cooling effect is required in the refrigerator, that is for example, when food products are placed in the refrigerator which require cooling, the temperature of water chamber 1 will rise, and the vapor removed will have a greater density. The suction pump runs at constant speed and in removing the vapor of reater density it removes more heat, which is the condition desired. In a like manner when thetemperature of the chamber 1 falls less heat will be removed therefrom because of the vapor removed being of lesser density. The temperature of the refrigerator will accordingly be maintained within a narrow range, this range being not sufficiently great to-interfere with the satisfactoryoperation of the apparatus. As the pump runs continuously no automatic devices for starting and stopping the driving motor are necessary.

While I have described my invention in detail in connection with the preferred embodiment thereof shown in the drawings, it will be obvious to those skilled in the art after understanding my invention that various changes and modifications may be made therein without. departing from the spirit or scope of the'invention, and I aim in the appended claims to cover all such changes and modifications as come within the scope of the invention.

What I claim is 1. In pumping apparatus." the combination of a vacuum pump cylinder, a piston therein, an inlet valve, mechanical means for operating said valve, and a zero-clearance exhaust valve.

2. In pumping apparatus, the combination of a vacuum pump cylinder, a piston therein, an inlet valve, means for moving said valve to open and closed positions,'periodically, independent of the pressure of gas on opposite sidesthereof, and a zero-clear ance outlet valve extending the full area of the cylinder. p

3. In pumping apparatus, the combination of a pump crank case, a pump for withdrawing gases from a chamber to be evacuated and delivering the same into said crank case, a ump for withdrawing the contents of sai crank case, and means for operating said pumps together.

4. In pumping apparatus, the combination of an air tight pump crank case, a suction pump delivering gases therein, a pump within said case withdrawing gases,-oil, or

condensed liquid therefrom, a crank withinsaid case, and means for operating both said pumps therefrom.-

5. In pumping apparatus, the combination of an airtight pump crank case, a suction pump delivering gases therein, a pump within said case withdrawing gases, oil, or condensed liquid therefrom, said pumps having pistons and inlet valves mechanically connected together, and means for operating said valves and pistons- 6. In pumping apparatus, the combination of a suction pump, a smaller pump, to

which gases withdrawn from a container are delivered by said first pump, means providing a bypass around said firstpump, leading to said smaller pump, a valve in said bypass, and means for closing said valve when a desired degree of vacuum is produced in said bypass by said smaller pump.

7. In pumping apparatus, the combination of a suctionv pump, a smaller suction pump, means for connecting said pumps to a space to be evacuated, and means rendering said first pump inefiective, until a desired vacuum has been produced in said space,-and then automatically rendering said said first pump operative to further evacuate said space.

8. In pumping apparatus, the combinaapplying lubricant within the cylinderof said first pump.

9. In pumping apparatus, the combination of a pump for withdrawing gases from a chamber to be evacuated, said pump having an air-tight crank case into which said.

gases are delivered, and a pump within said crank case for withdrawing the contents of said crank case to lower the pressure therein.

10. In pumping apparatus, the combination of a vacuum pump cylinder, a piston therein, an inlet valve to the cylinder with mechanical means for operating the same, a zero clearance exhaust valve, an air-tight crank case in communication with said exhaust valve, and means for maintaining a partial vacuum in said crank case.

11. In pumping apparatus, the combination of a suction pump and a smaller pump for evacuating a container, a passage to the inlet port of the larger pump, a shunt passage around said firstpassageand throu h which when open, the exhaust port of t e larger pump and the inlet port of the smaller pump are in communication with the container, at which time the larger pump is thereby rendered ineffective, and an automatically actuated valve rendered effective at a predetermined pressure in said shunt passage to close the same to render the large pump effective and to, cause the smaller pump to operate only upon the exhaust of the larger pump.

12. In, pumping apparatus, the combination of a cylinder and piston, a valve chamher at one end of the cylinder, an exhaust valve located within saidchamber, an in-,

-let port to the cylinder having a passage leading thereto, a branch passage connecting said first passage and valve chamber, an exhaust passage leading from said valve chamber for communication with suction means, and an automatically actuated valve rendered efiective at a predetermined pressure in the exhaust chamber te close the branch passage.

13. In pumping apparatus, the combination of a cylinder and piston, a valve chamconnecting said first passage and valve chamber, an exhaust passage leading from said chamber for communication with sucam e n: w

. ago-Ur tion means, an automatically operated valve for closing said shunt passage and comprising one or more hermetically sealed expansible containers containing a suitable fluid which will expand responsive to reduction of surrounding pressure to a predetermined point to close said shunt passage.

14-, In suction apparatus, the combination of a suction device for evacuating a container, said suction device having an inletand an outlet opening, a passage leading from the inlet opening for communication with the container, a smaller suction device having an inlet passage-commumcat1ng with the exhaust opening of the first sucv tive and thesecond suction device operates only upon the exhaust of the first device.

15. In pumpinug apparatus, the combination of a vacuum pump cylinder provided with an annular beveled seat at one end, an inlet port communicating with said seat, a sleeve slidablymounted in the cylinder and having a beveled end adapted to seat upon the beveled valve seat and serving as an inlet valve to close communication between the port and sleeve, means mechanically reciprocating sleeve to close and open the port, zero clearance exhaust valve above said and extending substantially the full er of the sleeve, and a piston within t sleeve movable at least to the upe of the sleeve and into entne exhaust valve, apparatus, the combinaa vacuum pump cylinder, a mechanically reciprocated sleeve within the cylinder, a reciprocating piston in the sleeve, the

sleeve acting as a cylinder lining and at one ene serving as an inlet valve member, a valve seat for said valve member, and a Zero clearance exhaust valve adjacent the valve seat engaged by the piston on its outward stroke,

1?. ln pumping apparatus, the combina tion of a vacuum pump cylinder, a mechanically reciprocated sleeve within the cylinder, a r procating piston in the sleeve, the sleeve 1g as cylinder lining and beveled 9 end to serve as an inlet valve member valve seat member having a beveled seat or the sleeve, said sleeve and valve seat n oer when in contact constituting the endear siding wall for the piston and with. which the piston has a substantially air-tight fit, and a zero clearance exhaust valve seated. upon the valve seat member and extending the full diameter of the sleeve, the piston being moved past the extremity of its guiding wall into engagement with the exhaust valve, whereby the entire fluid in the upper end of the piston chamber is displaced by the piston.

18. In pumping apparatus, the combination of a cylinder shell having an inlet port at its upper end, a reciprocating sleeve serving as a lining within said shell the upper end of which serves as an inlet valve, a valve chamber casing detachably secured to said cylinder shell, a valve seat member located at the upper end of the cylinder shell and upon which said sleeve is adapted to be seated to closethe inlet port, said valve chamber casing having a valve chamber formed therein, an exhaust valve within said chamber above said valve seat for closing communication between said sleeve ano chamber, a piston in the sleeve, means for reciprocating said piston to move the same beyond the valve seat into engagement with said exhaust valve, and means for reciprocating said sleeve.

19. In pumping apparatus, the combina end of which serves as an inlet valve, a valve chamber casing detachably secured to said cylinder shell, a valve seat member located at the upper end of the cylinder shell and upon which said sleeve is adapted to be seated to close the inlet port, said valve chamber casing having a valve chamber formed therein, an exhaust valve within said chamber above said valve seat for closing communication between said sleeve and chamber, means for reciprocating said piston to move the same beyond the valve seat into ei egcrnent with said exhaust valve, means for reciprocating said sleeve, an inlet passage within. valve chamber casing lead ing from said inlet port for communication with. a container to be evacuated, a branch passage within said casing connecting said first passage to said exhaust valve chamber, and an automatically actuated valve within said casing for closing said branch passage at a predetermined pressure in the valve chamber.

20. In pumping appe'ntus, the combination of an upright c3- shel a valve chamber casing detachably secure to the upper end of said cylinder shell, c.- valve seat member located be .en casing, a mechanically cc -ated islet r below said valve seat upon the same, der immediately -ieinber adapted rec cylinder and chamber, a piston in the cylin-.

der, means for reciprocating said piston to move the same beyond the valve seat into engagement with said exhaust valve, and

an exhaust passage leading from said exhaust valve chamber above the valve'seat member through the latter and through a portion ofthe cylinder shell. I

21. In pumping apparatus, the combination of an upright vacuum pump cylinder,

a mechanically reciprocated sleeve within the cylinder, areci rocating piston in the sleeve, the sleeve acting as a. cylinder lining and at its upper end serving as an inlet valve member, a valve seat at the end of the cylinder for said valve member to seat upon, an inlet port below the horizontal plane of said valve seat, a zero clearance exhaust valve having a seat above said inlet valve seat, an exhaust passage leading from said exhaust valve, and an mlet passage. leading from above said inlet valve seat transversely of the horizontal plane of said seat and to the inlet port below said seat,

22. In pumping apparatus, the combination ofan upright cylinder shell, a reciproeating sleeve serving as a lining within the shell and the upper end of which serves as an inlet valve, a valve chamber casing detachably secured to the upper end of saidcylinder shell, a valve seat member located between the upper end of said cylinder shell and said valve chamber casing and upon which said sleeve is adapted to be seated, an inlet port to the sleeve immediately below the valve seat member adapted to be closed by the sleeve when seated, an inlet passage in the valve chamber casing extending from above said valve seat member through the same to the inlet port, said valve chamber casing having a valve chamber formed therein, an exhaust valve within said chamber above said valve seat for closing communication between said sleeve and chamber, a piston in saidsleeve, means for reciprocating said piston to move the same beyond the valve seat into engagement with said exhaust valve, an air-tight crank case below the cylinder shell, means for evacuat- .ing said crank case, and an exhaust passage" 23.-In pumping apparatus, the combina- I tion of a cylinder casing, a reciprocating sleeve serving as a lining to said cylinder casing, a reciprocating piston within said sleeve, means for connecting said pumping apparatus with a container to be evacuated, whereby when the piston is operated a pressure below atmospheric pressure is maintained within the cylinder casing, asource of oil supply, and means for supplying oil from said source to a space between said cylinder casing and the reciprocating sleeve, from which space the oilwill besucked by said reduced pressure along the outer surface of the sleeve and over the edge of the same to the inner surface.

24. In pumping apparatus, the combination of a suction pump, a crank case into which the pump discharges, means for evacuating-said crank case of gases and. oil, an

oil separator into which the contents of said .matically lubricate the same.

25. In pumping apparatus, the combination of 'a vacuum pump cylinder, a valve seat member at one end of the cylinder having a beveled seat facing the cylinder, an inlet port communicatin with said seat, a sleeve slidably mounted in the cylinder and having a beveled end adapted to seat upon the beveled valve seat and serving as an inlet valve to close communication between the port and sleeve, means mechanically reciprocating said sleeve to close and open the port, a zero clearance exhaust valve above the valve seat member, said valve seat member havin a flat seat on its upper surface upon whic the exhaust valve is adapted to seat, said exhaust valve extending substantially the full diameter of the sleeve, and a piston within the sleeve movable into engagement with the exhaust valve.

In testimony whereof I have signed my name to this specification.

' KENNETH L. CURTIS. 

